Method for producing polishing wheel



Dec- 27, 1966 P. E. SCHAFFNER 32%,2

METHOD FOR PRODUCING POLISHING WHEEL Original Filed April 29, 1959 United rates l atent Qfilice Siddfidii Patented Dec. 27, 1966 3,294,502 METHUD EUR PRQDUCENG PQLISHKNG WHEEL Paul E. Schatfner, Wexford, Pa, assignor to Schafiner Manufacturing Company, line, Ernsworth, Pa, a corporation of Pennsylvania Original application Apr. 29, 1959, Ser. No. 8%,647, now Patent No. 3,206,894,, dated Sept. 21, 1965. Divided and this application May 9, 1962, Ser. No. 193,446

7 Claims. (Cl. 51-293) This application is a division of application Serial No. 809,647, filed April 29, 1959 and now US. Patent No. 3,206,894 to Paul E. Schatfner for Polishing Wheel and Method for Producing Such Wheel.

This invention relates to the polishing or buffing art and has particular relationship to polishing wheels. The expression polishing wheel is used in this application in its general sense and is meant to include within its sco e buffing and finishing as well as polishing wheels.

This invention in its specific aspects concerns itself with polishing wheels composed a plurality of flaps of abrasive material. Usually such flaps are abrasive on one side and smooth on the other. Such wheels are in the form of an annulus, usually (but not necessarily), with the abrasive surface of each flap contiguous to a smooth surface of the adjacent flap and with the radially inner ends of the flaps bonded together by an adhesive between the surfaces of the flaps.

The making of such wheels, in accordance with the teachings of the prior art, has disadvantages. The bonding of the inner surfaces presents a serious problem.

In accordance with the teachings of the prior art, the annulus is provided with flanges, one of which has an opening in the center and the adhesive is injected through this opening while the annulus is rotated at a substantial speed about a horizontal axis. The adhesive is injected between the flaps by centrigual force. The injection of the adhesive presents difficulties. In addition the hubs of wheels of this type have been found to be fragile and to crack during shipment.

There are disadvantages in the prior art wheels themselves. In use the wheels are rotated at a high speed, the abrasive surfaces of the flaps successively engaging the work. Excessive heat develops during such use and the flaps are charred materially shortening the life of the whlelels. In addition, the ends of the flaps fray substanha y.

It is then a specific object of this invention to provide a method for making polishing wheels composed of abrasive flaps which shall not have the disadvantages of prior art methods.

More specifically stated, it is an object of this invention to provide a low-cost readily usable method for making polishing wheels of abrasive flaps, the hubs of which shall be resistant to fracture.

A further specific object of this invention is to provide a low-cost readily usable method of bonding the surfaces of the radially inner ends of the flaps in the making of a polishing wheel or flaps formed into an annulu and iparticularly in the making of a wheel formed of abrasive aps.

Still another specific object of this invention is to provide a low-cost method of forming a fracture-resistant hub of a polishing wheel in the form of an annulus of flaps and particularly of abrasive flaps.

It is an object of this invention to provide a novel method of producing a polishing wheel in the form of an annulus of flaps having important advantages in the making of wheels with abrasive flaps but also applicable to wheels in which the flaps are of nonabrasive material, and it is another object of this invention to provide such a wheel.

This invention, in one of its specific aspects, arises from the realization that in the practice of the prior art method the distribution of adhesive over the surfaces of the radially inner edges of the flaps of the annulus is not uniform because of the manner in which the annulus is rotated to inject the adhesive between these surfaces. This disadvantage and the difficulties in applying the adhesive are both overcome in accordance with this invention by confining the liquid adhesive in a horziontal pool within the annulus and then rotating the annulus and adhesive about a vertical axis. During this rotation the adhesive is injected uniformly between the flaps. It has been found that highly effective penetration can be produced even where the flaps are tightly packed. The speed of rotation and the viscosity of the adhesive are correlated so that the adhesive is injected only over a suitable distance from the inner periphery of the annulus towards the outer periphery of the annulus and not beyond this distance. After the adhesive is injected it is cured, and it has been found that a wheel with a strongfracture-resistant annulus results.

The annulus and adhesive may be rotated together. But in accordance with an important specific aspect of this invention the annulus and adhesive are rotated separately at difierent speeds. The relative rotation of the annulus and adhesive assures uniform distribution of the adhesive over the radially inner ends of the annulus and the uniform penetration of the adhesive between the surfaces contiguous to these ends.

The fracture-resistance is further increased by mounting the flaps on a resilient ring which serves not only to facilitate the formation of the flaps into an annulus but also in strengthening the hub. In accordance with one aspect of this invention the ring may be solid. During the formation of the annulus the ring is inserted in the flaps through slits extending from the radially inner ends engaging an opening at the ends of the slits. When the flaps extend around substantially the whole ring, the adjacent flaps at one point of the ring are separated and clamped under substantial pressure and additional flaps are inserted between the separated flaps. When the pressure is relieved the flaps are thus tightly packed on the ring.

The ring may also be split with the ends interlocked by notches or the like. In this case the flaps need not have slits but must have holes near the edges which are to form the radially inner periphery of the annulus. In this case the ring is separated at the split and the fiaps in bundles with the holes aligned are slipped over the ends of the ring. When the flaps are tightly packed the ring is permitted to spring back so that its ends interlock.

When the annulus is assembled flanges are placed on each side of hub to keep the annulus aligned. Adhesive is then applied. The adhesive should penetrate beyond the ring so that the ring serves as reinforcement for the adhesive analogously to the metal in reinforced concrete. The ring should preferably be positioned in the region where the hub is tensioned when stress is applied to it.

The charring of the flaps during use i prevented by cooling the wheel. For this purpose the wheel is provided with cooling slots extending radially inwardly. Each fiap has at least one slot extending inwardly from the radially inner end. When the flaps are formed into an annulus the slots are aligned to form a slot having the configuration of a disc. The slots extend beyond the parts of the surfaces where the adhesive penetrates.

When the annulus is being prepared for rotation to inject the adhesive the slot is masked by tape which may be removed before or after curing. The slot provides a passageway for cooling air.

To suppress the fraying, the flaps are cut out from the matrix cloth on a bias.

The novel features considered characteristic of this invention are disclosed generally above. The invention itself both has to its organization and as to its method of operation, together with additional objects and advantages thereof, will be understood from the following description of specific embodiments taken in connection with the accompanying drawings, in which:

FIGURE 1 is a view in side elevation of a flap used in the practice of this invention;

FIG. 1a is a view in side elevation showing how the flaps shown in FIG. 1 are mounted in a solid ring to form an annulus;

FIG. 2 is a view in side elevation showing how the flaps shown in FIG. 1 (or like flaps without slits) are mounted on a split ring to form an annulus;

FIG. 3 is a fragmental view showing how the ends of the ring interlock;

FIG. 4 is a view in longitudinal section showing apparatus of one type for practicing this invention;

FIG. 5 is a view in longitudinal section showing apparatus of another type for practicing this invention;

FIG. 6 is a view in longitudinal section showing apparatus of a third type for practicing this invention;

FIG. 7 is a view in perspective showing a polishing wheel in accordance with this invention;

FIG. 8 is a view in longitudinal section showing the manner in which a polishing wheel in accordance with this invention is used;

FIG. 9 is a View in perspective showing a polishing wheel in accordance with a modification of this invention; and

FIG. 10 is a view in section showing a polishing wheel in accordance with another aspect of this invention.

The flap 11 in accordance with this invention is of generally rectangular form with a stem 13 extending from one side of the rectangle. The stem has notches 15 and 17 and 19 and 21 which are symmetrically disposed with reference to the longitudinal axis of the stem. The stem 13 also has a slit 23 (FIG. 6) which terminates in a hole 25 and a pair of slots 27. The slots 27 extend an appreciably greater distance from the end of the stem 13 than the hole 25. The flap 11 is preferably coated with an abrasive on one side and is smooth on the opposite side.

In the practice of this invention a large number of flaps 11 are formed into an annulus in which the flaps are tightly packed. The annulus is produced by stringing the fiaps 11 on a solid ring 30. Bundles of the flaps 11 are assembled with the slits 23 and the holes 25 aligned and are mounted on the ring 30 by slipping the ring 30 through the slits 23 until the ring 30 engages the holes 25. When the ring 30 is substantially filled, adjacent flaps 32 and 34 at one point are pressed back and clamped, and additional flaps 11 are slipped onto the ring 30. Flaps 32 and 34 are then released and a tightly packed annulus is formed.

The flaps 11 may also be strung onto a resilient split ring 31. In this case the slits 23 may be omitted. The ends 33 and 35 of the ring 31 are provided with mating notches 37 and 39 which overlap so that in the closed posiiton the ring 31 is locked by the engagement of the notches 37 and 39.

In forming the annulus the ring 31 is opened and the flaps 11 are mounted on the ring by threading the holes 25 in the flaps over the split ends of the ring. A plurality or bundle of flaps may be strung onto the ring during each stringing operation. Each bundle should be assembled so that the slits 23 are coextensive and the slits of the bundle should be passed together over the ring 31.

When a sufllcient number of flaps 11 have been strung on the ring 31 to form a tightly packed annulus the ends 33 and 35 are released and permitted to snap into engagement. The annulus 40 which is thus formed has a hub supported on ring 31, circular grooves formed by the 4 notches 15, 17, 19 and 21 and circular slots formed by the slots 27. v

The rings 30 and 31 may be composed of metal. While mild steel or aluminum may be used, spring steel is preferred in certain situations.

The annulus is now provided with a solidified hub. For this purpose the stems 13 are secured together by an adhesive. The adhesive may be formed by combining a resin such as HYSOL 2030 or Bakelite ERL-2774 with a hardener such as diethylene triamine, Bakelite ZZLD- 0814 or combinations of the diethylene triamine and Bakelite ZZLD-O8l4. The adhesive consists of 100 parts by weight of resin and 10 to 40 parts by weight of hardener. The hardener may have any composition between 100% triamine and 0 of 0814 and 0 0f triamine and 100% of 0814. HYSOL 2030, Bakelite ERL 2774, and Bakelite ZZLD0814 are epoxy resins. HYSOL 2030 is sold by Houghton Laboratories Inc. of Olean, NY. and is described in Houghton Technical Data #20-1 dated February 1958. ERL 2774 is described in Epoxy Technical Bulletin No. 4 of Union Carbide Corp. and ZZLD-0814 in its New Product Engineering Department Technical Release No. 7.

The adhesive so formed is a liquid and is injected between the surfaces of the stems 13 by centrifugal force. The higher the triamine the lower the viscosity of the adhesive.

For this purpose, a receptacle 41 (FIG. 4) mounted on a turntable 42 to rotate about a vertical axis is provided. The receptacle 41 includes a cylindrical wall 43 and the space within which is closed by upper and lower plates 45 and 47. The lower part 49 of the wall 43 is solid and the upper part 51 is perforated. The lower plate 47 may be secured to the lower part 49 of the wall 43, for example, by welding and has a projection 53. An annular trough is thus formed between the projection 53 and the part 49 in which the liquid adhesive 55 is disposed. The upper plate 45 may be fiat. This plate may be removably mounted on the wall 43. Each of the plates 45 and 47 extends beyond the wall 43 and the extending portions are provided with annular projections 61, 63, and 67 adapted to engage the grooves 15, 17, 19, 21 of the annulus 40.

In the practice of this invention the plate 45 is removed from the wall 43 and the adhesive 55 is poured into the trough between part 45 and projection 53. The circular slots 27 in the annulus 40 are then closed by strips of adhesive tape 71 extending around the radially inner wall of the annulus 40 at the slots 27. The annulus 40 is then mounted encircling the wall 43 with its grooves 17 and 21 engaging the projections 65 and 67. To facilitate removal of the annulus after treatment, polyethylene sheet or silicone parting agent (not shown) may be interposed between the grooves 17 and 21 and the projections 65 and 67. The top 45 is then mounted on the wall 43 with the projections 61 and 63 engaging the grooves 15 and 19. Polyethylene sheet or a conventional mold release or parting agent (not shown) may also be interposed in this case between the projections 61 and 63 and the grooves 15 and 19. The annulus 40 should be held tightly between the plates 45 and 47.

The assembly 41-40 is then mounted on the turntable 42 and rotated. The rotation causes the adhesive 55 to rise along the wall 43 and be projected through the openings 73. The adhesive impinges on the radially inner periphery 75 of the annulus 40 and because the rotation of the annulus 40 is injected between the surfaces of the stems 13 of the flaps 11. Suificient adhesive flows down the wall 75 to provide for coating of the portions of the surfaces of the stem 13 opposite the part 49 of the wall 43. The speed of rotation should be so coordinated with the viscosity of the adhesive that the adhesive is injected only to the region just beyond the ring 31 and not beyond the inner ends of the slots 27. The following table shows relationships between viscosity, speed and time of injection which have proven satisfactory for the above-described adhesives. The viscosity was set in each case by adjusting the proportions of the hardeners diethylene triamine and Bakelite ZZLD-08l4.

After being treated as just disclosed the annulus 40 is removed from the receptacle 41 and the adhesive is cured by heating the treated annulus. The tape 71 is then removed. A polishing wheel 31 (FIG. 7) with a solid hub 83 which is not fragile is thus produced. Because of the rotation about a vertical axis the adhesive is uniformly distributed over the hub. The ring 31 serves as reinforcement. The slots 27 which are free of adhesive throughout and communicate with the separable parts of the flaps 11 serve to ventilate the wheel in use.

When the wheel 81 is to be used, it is provided with end plates 91 and 93 having projections 95 which engage the grooves 15, 17, 19, 21. The plates 31 and 93 have central openings through which a shaft 97 passes. The shaft 97 is threaded and is held in firm engagement with the plates 91 and 93 by nuts 99. The plates 91 and 93 have perforations 101 in their faces.

In use the shaft 97 is rotated, rotating the wheel 81. The outer periphery of the wheel 81 is in polishing engagement with the work While the Wheel is rotated. The heat developed by the polishing is to a large extent carried away by the cooling air flowing through the holes 101, the slots 27 and between the unjoined parts of the flaps 11.

To improve the distribution of the adhesive the annulus 41] is rotated at a different speed than the adhesive. This is accomplished with apparatus as shown in FIG. 5 which includes a cup-shaped receptacle 111 having a solid base 113 and a wall 115 which is solid in the lower part and perforated in the upper part. A vertical shaft 117 extends from the center of the base 113. The adhesive 119 is disposed in the lower part of the receptacle 111. The apparatus also includes lower and upper plates 121 and 123 each having annular projections 125 and 127 adapted to engage the grooves 15, 1'7, 19 and 21 in the annulus 40. A- hollow shaft 131 extends from the lower plate 121 and this plate is also provided with an opening coaxial with the shaft 131 adapted to accommodate the shaft 117.

When this apparatus is to be used the plate 121 is mounted on a bearing plate 133 with a bearing ring 135 extending from plate 121 engaging bearings 137 in plate 133. The receptacle 111 with the adhesive 119 in the base is mounted on plate 121 with the shaft 117 extending through plate 121 and shaft 131. The shaft 117 extends below shaft 131. The annulus 41) (with slots 27 taped) is then mounted on plate 121 (preferably with polyethylene sheet or a suitable mold release agent interposed between 17, 21 and 125). The upper plate 123 is then mounted on the annulus 41) and bolted to the lower plate 121 by bolts 141 passing between the receptacle 111 and the annulus 41}. The shafts 117 and 131 may then be provided with driving pulleys 143 and 145 and the annulus assembly to-121423 and receptacle 111 rotated at different speeds. The direction of rotation may be the same or opposite.

The speed of the receptacle is so related to the viscosity of the adhesive 119 that the adhesive is projected on the radially inner surface 75 of the annulus. The speed of the annulus is so related to the viscosity of the adhesive that the adhesive is injected between the surfaces of the stems 13 as described above. After this treat- 6 ment the annulus is cured and a polishing wheel 81 as described above is produced.

The adhesive may also be injected into the annulus 40 under pressure. For this purpose the apparatus shown in FIG. 6 is provided. This apparatus includes a flange stub 161 and cooperative plate 163. The flange 165 of the stub 161 includes projections 167 adapted to engage the grooves 19 and 21. The plate 163 has like projections 169. The annulus 40 is compressed between the flanges 165 and 163 by bolting the plate 163 to the stub 161. O-rings 171 and 173 are compressed between the grooves 15 and 19 and the projections 167 and 169. Adhesive is then injected under pressure through openings 175 in the plate 163. The pressure causes the adhesive to penetrate between the surfaces of the stems 13. After this treatment the annulus 411 is cured.

A modified wheel 191 in accordance with this invention is shown in FIG. 9. This wheel is made up of flaps 193 which do not have slots 27. The flaps 193 may be formed into an annulus and treated in the same manner as the flaps 11. A wheel 191 having a solid hub is thus formed. After the wheel is formed holes 195 are drilled through the hub. This object may be accomplished by separating the unjoined ends of the flaps 193 at selected regions and drilling through the hub at these points. The holes 195 serve for ventilation purposes.

In the wheel shown in FIG. 10 the flaps 11 and spacers 301 alternate. Thes pacers 301 may be made of wood or cardboard. The wheel shown in FIG. 10 may be joined at the radially inner ends in the same way as the other polishing wheels.

While preferred embodiments of this invention have been disclosed herein, many modifications thereof are feasible. This invention then is not to be restricted except insofar as is necessitated by the prior art.

I claim as my invention:

1. The method of forming a polishing wheel from a plurality of flaps comprising forming said flaps into an annulus, confining a liquid epoxy-resin adhesive within the opening of said annulus in communication with the ends of said flaps bounding said opening, rotating said adhesive at a first predetermined speed so that said adhesive is caused by centrifugal force to penetrate into said ends of said flaps, rotating said annulus at a second speed difierent from said first speed so that said adhesive which has penetrated into said ends is caused by centrifugal force to penetrate between the surfaces contiguous to said ends, and thereafter heating said adhesive to cure said adhesive so that said adhesive hardens forming said annulus into a wheel with a substantially solid hub, the viscosity of said adhesive being so related to said first and second speeds that said adhesive penetrates between said contiguous surfaces only for a predetermined distance along said flaps, said distance being such that said flaps extend freely from said hub over a substantial portion of their length.

2. The method of forming a polishing wheel from a plurality of flaps comprising forming said flaps into an annulus, providing a chamber bounded by the ends of said fiaps defining the inner opening in said annulus, injecting an epoxy-resin adhesive under pressure into said chamber to cause said adhesive to penetrate between the portions of said flaps near said ends of said flaps, said pressure being set with respect to the viscosity of said adhesive so that said adhesive penetrates between said portions only a predetermined distance, and thereafter heating said adhesive to cure said adhesive so that said adhesive hardens forming said annulus into a wheel with a substantially solid hub, said distance being such that said flaps extend freely from said hub over a substantial portion of their length.

3. The method of forming a polishing wheel from a plurality of flaps comprising forming said flaps into an annulus, providing an annular chamber bounded by the ends of said flaps defining the inner opening in said annulus on one side and by a solid wall on the opposite side, injecting an epoxy-resin adhesive under pressure into said chamber to cause said adhesive to penetrate between the portions of said flaps near said ends of said flaps, said pressure being set with respect to the viscosity of said adhesive so that said adhesive penetrates between said portions only a predetermined distance, and thereafter heating said adhesive to cure said adhesive so that said adhesive hardens forming said annulus into a wheel with a substantially solid hub, said distance being such that said flaps extend freely from said hub over a substantial portion of their length.

4. The method of forming a polishing wheel from a plurality of flaps comprising forming said flaps into an annulus, confining a liquid epoxy-resin adhesive in the opening of said annulus in a substantially horizontal pool in communication with the ends of said flaps bounding said opening, rotating at least said adhesive at a predetermined speed about a vertical axis so that said adhesive is caused by centrifugal force to penetrate by movement generally horizontally generally symmetrically about said axis between the inner surface of said flaps, and thereafter heating said adhesive to cure said adhesive so that said adhesive hardens forming said annulus into a wheel with a substantially solid hub, the viscosity of said adhesive being so related to said speed that said adhesive penetrates between said inner surfaces only for a predetermined distance along said flaps, said distance being such that said flaps extend freely from said hub over a substantial portion of their length.

5. The method of forming a polishing wheel from a plurality of flaps and a solid ring, each fiap having a slit on one end thereof terminating in a hole within said flap, said hole being dimensioned to accommodate said ring, the said method comprising, forming a tightly packed annulus of said flaps on said ring by slipping said ring through the slits in said flaps to a position in which said ring extends through said holes in said flaps, said annulus having a central opening, confining a liquid adhesive in said opening in communication with said one end of said flaps, rotating said annulus at a predetermined speed so that said adhesive is caused by centrifugal force to penetrate between the surfaces of the flaps at said one end, and thereafter heating said adhesive to cure said adhesive so that said adhesive hardens forming said annulus into a wheel with a substantially solid hub.

6. The method of forming a polishing wheel from a plurality of flaps and a solid ring, each fiap having a slit on one end thereof terminating in a hole within said flap, said hole being dimensioned to accommodate said ring, the said method comprising, forming a tightly packed annulus of said flaps on said ring by slipping said ring through the slits in said flaps to a position in which said ring extends through said holes in said fiaps and forming a substantially solid central hub on said annulus by injecting an adhesive between the portion of said flaps in the region of said ring to cause said portion of said flaps to solidify.

7. The method of forming a polishing wheel comprising an annulus of flaps extending from a substantially solid core at the center formed by the adhesion of the ends of said flaps at said core, the said method comprising the steps of forming the annulus by slipping flaps edgewise onto a solid ring through slits near said ends of said flaps which form the core, the slit of each said flap terminating in a hole that engages the ring, sufiicient flaps being slipped on said ring to form a preliminary annulus extending substantially around the whole ring; thereafter separating the adjacent flaps at one point of the preliminary annulus and clamping said last-named flaps apart at said point and slipping additional flaps edgewise over the ring through slits near their ends which do terminate in holes that also engage said ring, a sufficient number of additional flaps being slipped over the ring to produce a tightly packed annulus of flaps, applying an adhesive to the end of said flaps which form the core and thereafter curing the adhesive to form a solid core.

References Cited by the Examiner UNITED STATES PATENTS 2,749,224- 6/1956 Block 5l293 2,808,689 10/1957 Thomson et a1. 5l297 2,843,469 7/1958 Miller et al 5l297 2,991,165 7/1961 Meyer et al. 5l293 3,102,010 8/1963 Lang 5l297 3,206,786 9/1965 Sax et a1. 15-230.1

ALEXADER H. BRODMERKEL, Primary Examiner. MORRIS LIEBMAN, Examiner.

D. J. ARNOLD, Assistant Examiner. 

1. THE METHOD OF FORMING A POLISHING WHEEL FROM A PLURALITY OF FLAPS COMPRISING FORMING SAID FLAPS INTO AN ANNULUS, CONFINING A LIQUID EPOXY-RESIN ADHESIVE WITHIN THE OPENING OF SAID ANNULUS IN COMMUNICATION WITH THE ENDS OF SAID FLAPS BOUNDING SAID OPENING, ROTATING SAID ADHESIVE AT A FIRST PREDETERMINED SPEED SO THAT SAID ADHESIVE IS CAUSED BY CENTRIFUGAL FORCE TO PENETRATE INTO SAID ENDS OF SAID FLAPS, ROTATING SAID ANNULUS AT A SECOND SPEED DIFFERENT FROM SAID FIRST SPEED SO THAT SAID ADHESIVE WHICH HAS PENETRATED INTO SAID ENDS IN CAUSED BY CENTRIFUGAL FORCE TO PENETRATE BETWEEN THE SURFACES CONTIGUOUS TO SAID ENDS, AND THEREAFTER HEATING SAID ADHESIVE TO CAUSE SAID ADHESIVE SO THAT SAID ADHESIVE HARDENS FORMING SAID ANNULUS INTO A WHEEL WITH A SUBSTANTIALLY SOLID HUB, THE VISCOSITY OF SAID ADHESIVE BEING SO RELATED TO SAID FIRST AND SECOND SPEEDS THAT SAID ADHESIVE PENETRATES BETWEEN SAID CONTIGUOUS SURFACES ONLY FOR A PREDETERMINED DISTANCE ALONG SAID FLAPS, SAID DISTANCE BEING SUCH THAT SAID FLAPS EXTENDIND FREELY FROM SAID HUB OVER A SUBSTANTIAL PORTION OF THEIR LENGTH. 